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Eliminate Slop and Restore Direct Gear Engagement on Your 2004-2021 Subaru STi
The Kartboy KB-001-01005 Solid Shift Joint replaces the compliant rubber bushing at the base of the 6-speed shift lever on 2004-2021 Subaru STi models. The factory joint uses a rubber-isolated pivot that flexes under load, creating shift slop, imprecise gate feel, and missed shifts during aggressive driving. The KB-001-01005 replaces that rubber with a solid machined joint, providing a direct mechanical connection between the shifter and the transmission for noticeably shorter throws and sharper gate definition.
Key Features
- Solid machined construction eliminates the rubber deflection of the OEM shift joint
- Direct bolt-in replacement for the factory 6-speed shift joint on 2004-2021 Subaru STi
- Reduces perceived throw length by tightening the mechanical slop at the pivot point
- Improves gate definition and accuracy during fast sequential shifts
- Compatible with stock shifter, short throw shifters, and Kartboy short throw kits
- Machined to OEM dimensional spec for straightforward installation
- Durable construction for long-term use under track and street conditions
Fitment
| Year Range | Make | Model | Trim |
|---|---|---|---|
| 2004-2021 | Subaru | Impreza / WRX | WRX STI |
Specifications
| Detail | Value |
|---|---|
| Part Number (MPN) | KB-001-01005 |
| Application | 2004-2021 Subaru STi 6-Speed Transmission |
| Construction | Solid machined joint |
| OEM Replacement For | Factory rubber shift joint / pivot bushing |
| Compatible Transmissions | 6-Speed (STi) |
| UPC | 850014195672 |
What's Included
- 1x Kartboy KB-001-01005 Solid Shift Joint
About Kartboy
Kartboy is a Subaru-specialist performance parts manufacturer known for producing short throw shifter kits, shift linkage components, and suspension bushings that improve driving engagement without sacrificing street usability. All Kartboy components are engineered and manufactured to precise dimensional tolerances for bolt-on installation on the specific Subaru platforms they are designed for.
Frequently Asked Questions
What does the Kartboy KB-001-01005 solid shift joint do?The KB-001-01005 replaces the factory rubber pivot bushing at the base of the 6-speed gear lever on 2004-2021 Subaru STi models. The OEM rubber joint flexes under shifting force, causing imprecise gate feel and missed shifts. Replacing it with a solid joint tightens the mechanical connection for direct, accurate shift input.
Will the KB-001-01005 make my shifts noticeably shorter?The solid joint removes the rubber deflection inherent in the OEM pivot, which translates into a perceptibly tighter and more direct shift feel. For the most dramatic throw reduction, pairing the KB-001-01005 with a Kartboy short throw shifter kit delivers the maximum effect.
Is the Kartboy KB-001-01005 compatible with my short throw shifter?Yes. The KB-001-01005 is compatible with the stock Subaru STi shifter as well as Kartboy and most third-party short throw shifter kits. It addresses the pivot joint separately from the lever arm geometry, so it works alongside throw-reducing kits without conflict.
Does installing the KB-001-01005 require removing the transmission?No. The solid shift joint is accessed from inside the cabin or from underneath the vehicle at the shift linkage, depending on the specific model year. The transmission does not need to be removed for this installation.
Will the Kartboy solid shift joint increase NVH or vibration into the shifter?A solid joint transmits more mechanical feedback than rubber, which means some additional vibration may be felt at the knob under certain conditions. Most STi drivers find this feedback informative rather than intrusive, particularly during track use. Street-only drivers sensitive to NVH should consider this before installing.
Does the KB-001-01005 fit both the USDM and JDM 2004-2021 Subaru STi?The KB-001-01005 is designed for the 6-speed transmission used in the 2004-2021 Subaru STi. Confirm your specific transmission code matches the 6-speed STi unit if you are installing on a JDM-spec vehicle, as JDM and USDM STi transmissions share the same basic architecture on this platform.
Is the Kartboy KB-001-01005 a direct drop-in replacement?Yes. The KB-001-01005 is machined to the same dimensional interface as the OEM rubber shift joint, so it installs in the factory location without modification to the shifter housing, linkage, or chassis.
Can I install the KB-001-01005 on a 5-speed Subaru WRX?No. The KB-001-01005 is designed for the 6-speed transmission found in the STi. For 5-speed WRX shift joint upgrades, Kartboy offers separate components designed for the 5-speed linkage architecture.
Installation Instructions
- Shift the transmission to neutral and engage the parking brake before beginning any disassembly.
- Remove the shift knob and shift boot from the center console.
- Locate the shift joint at the base of the lever and remove the retaining hardware securing the factory rubber joint.
- Remove the OEM rubber shift joint from its pivot location.
- Install the Kartboy KB-001-01005 solid shift joint in the factory position, ensuring proper seating at the pivot interface.
- Reinstall retaining hardware to factory torque specification.
- Reinstall the shift boot and shift knob.
- Cycle through all gears and confirm smooth engagement before test driving.
WARNING: This product can expose you to chemicals including lead and phthalates, which are known to the State of California to cause cancer and reproductive harm. For more information go to www.P65Warnings.ca.gov.
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